Recently, I received a Pro-2021 off of Ebay. The radio did not come with the whip antenna that sticks out the top. I replaced the external antenna connectors with a chassis mount BNC. I notice that when I connect the external antenna to the radio it attenuates the signal. If I just use an 18" piece of copper the signal is much stronger. I built a ground plane antenna for the 159Mhz band and the SWR are low 1:1. I was hope someone could offer some suggestions. It's as if the antenna is loading down the receive circuit.
Thank you
Thank you
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